The partial coating of backing materials with pressure-sensitive self-adhesive compositions is a known technique, whether the self-adhesive compositions are applied in patterned form, for example by screen printing (DE-C 42 37 252), in which case the domes of adhesive can also differ in their size and/or distribution (EP-C 353 972), or by intaglio printing, in lines which interconnect in the longitudinal and transverse direction (DE-C 43 08 649). In this case the preferred degree of wetting of the backing materials is from 40 to 70%.
It is also known that backing materials detachable especially without residue can be coated with self-adhesive materials.
DE-A 42 37 252 uses special geometries to achieve the absence of residue. It is entirely possible in this case to coat air-permeable backings or else film-based backings. DE-A 196 28 268 describes a self-adhesive, air-permeable and moisture-permeable sheetlike structure which has been produced in a non-continuous procedure in the form of screen printing, intaglio printing or flexographic printing. DE-A 196 28 294 describes a self-adhesive plaster which has been produced with a pressure-sensitive adhesive by screen printing, intaglio printing or flexographic printing.
In this case, the adhesive composition is applied in discrete patterns.
It is also known in the textile industry that partially coated backing materials can be transferred. EP-A 0 675 183 describes a process which transfers hotmelt pressure-sensitive adhesive geometries to a specially crosslinked substrate. A derivation for self-adhesive products is not described. The use of a coated roller as an auxiliary backing for the transfer has also already been described (CH 648 497), which again does not address self-adhesive products. The possibility of the simultaneous deliberate and permanent deformation of the discrete geometries and of the parameters which influence them, and also apparatus for realizing these parameters, is not embraced here.    DE-U 83 36 583.4 describes a pressure-sensitive adhesive sheetlike structure which can be redetached without residue.    DE-A 38 05 223 discloses a pressure-sensitive adhesive sheetlike structure with an increasing number of attachment points.    DE-A 196 20 107 describes an at least partially coated backing material where the adhesive composition is a foamed hotmelt.    DE-A 196 31 422 describes a self-adhesively treated backing material with a particularly strongly adhering hotmelt adhesive composition.    DE-A 34 33 293 discloses a self-adhesive transparent film and its process.
All of the above products and processes, respectively, have the common feature that either coating with domes is not mentioned or, if domes are applied to a backing material, these domes are not deformed.
Doping of partially coated self-adhesive tapes is also described: in U.S. Pat. No. 4,699,792, for instance, a plaster device of this kind is described, comprising active substances.
Sheetlike structures which can be redetached without residue are obtainable commercially in block form, inter alia, under the name “tesa Notes”® from Beiersdorf.
As backing materials, numerous materials on a film, woven, knit, nonwoven, gel or foam basis have already been described and are also being employed in practice.
In the medical sector, special requirements are placed on the backing materials. The materials must be compatible with the skin, generally permeable to air and/or water vapour, and also easy to model and conformable. As a result of these requirements, a very thin or soft backing is frequently preferred. For handling and in use, however, the backing materials are also required to be of sufficient strength and possibly of limited extensibility. Furthermore, the backing material should retain sufficient strength and low extensibility even after becoming wet through.
Specific applications, an example being adhesive backings for functional tape dressings for the prophylaxis and therapy of injuries, disorders and altered states of the locomotor system, require non-elastic backings having high strength in the direction of stress. This is achieved by using wovens, usually of cotton or viscose. Backing materials of this kind, particularly with appropriately high basis weight, are generally costly. High flexibility can be achieved only by means of a woven of relatively low strength. When such a fabric is stressed, however, it generally exhibits a certain degree of extension, which is undesirable for the application.
The advantage of the patterned application of the adhesive to the backing material is that the adhesive materials, given an appropriately porous backing material, are permeable to air and water vapour and, in general, are readily redetachable.
Especially in the case of medical applications, the partial application makes it possible for the transepidermal water loss to be dissipated through regulated channels, and improves the evaporation of perspiration from the skin, especially when the backing materials used are permeable to air and water vapour. This prevents skin irritations induced by instances of buildup of body fluids. The dissipation channels employed allow such fluids to be conducted away even when a multi-ply dressing is used.
A disadvantage of these products, however, is that if the area covered by the adhesive film, which is impermeable per se, is too large there is a corresponding reduction in the permeability to air and water vapour, and the consumption of adhesive composition rises, and also, if the area covered by the adhesive film is too small, the adhesion properties suffer, i.e. the product is detached too readily from the substrate, in particular from the skin, and especially in the case of heavy, textile backing materials. Permanent bonding is therefore not possible.
In the case of the pressure-sensitive self-adhesive compositions referred to, the compositions may be present in a carrier matrix for the purpose of processing. The term carrier matrix is understood to refer to common organic or inorganic solvents or dispersion media.
Systems without a carrier matrix are referred to as 100% systems and are likewise not unknown. They are processed in the elastic or thermoplastic state. A common mode of processing is that of the hotmelt.
Pressure-sensitive hotmelt adhesive compositions of this kind have also already been described in the prior art. They are based on natural or synthetic rubbers and/or other synthetic polymers.
An advantage of the 100% systems is that they avoid an operation of removing the carrier matrix, i.e. the auxiliary media, thereby raising the productivity of processing and at the same time reducing the expenditure on machinery and the energy costs. In addition, this reduces the occurrence of residues of the carrier matrix, which in turn, is to the benefit of a reduction in the allergenic potential.
The object of the invention was to provide a process for producing a partially self-adhesively treated backing material, treated on at least one side, where the backing material, owing to its treatment—i.e., to the applied form and properties of the adhesive composition and to the material properties of the backing material—serves a functionally appropriate purpose for various fixings, especially for medical products, and in doing so offers both functional and economic advantages.